Thursday, September 27, 2012

I like the thought experiment “What would you study
if you could start your career over at some previous time knowing what you now
know?” The answers vary widely, but discounting the few that say “anything but
biology” or “investment banking” or the like, people usually talk about some
study organism that they think is really cool. For me, I have periodically
thought that it would be great to go back in time and discover and describe for
the first time those really bizarre animals that came to scientific attention
only recently: naked mole rats or gastric brooding frogs or coelacanths and so
on. At other times, I wish I could have been there to describe really cool
adaptive radiations of animals – with an obvious one being ants: honey pot
ants, leaf cutter ants, slave making ants, army ants, and so on. Recently,
however, a trip to the island of Kyushu in Japan crystalized another
possibility.

I have always thought praying mantises were really amazing
creatures: from their stretched bodies that can nonetheless fly to their deadly
front legs to their bizarrely mobile heads that look vaguely humanoid. (They
are apparently the only insect that can look over its shoulder.) But all of my
experience with them was from pictures in books or sequences in movies – like
the BBC one where you think it is going to eat something and then it instead
gets eaten by a chameleon. I had only ever seen one in the wild before but that
was when I was in line to get into a Lollapalooza concert in eastern Washington,
and so I didn’t really have much time for appreciation. This summer turned
things around.

The first thing that happened was that my 6 year-old
daughter, Cedar, found one in the field at the barn where my wife, Heather,
keeps her horse, Delmar. They brought it home and put it in a terrarium and we
began to feed it grasshoppers. It was deadly. We could put in 5 grasshoppers
and within just a half an hour they would all be dead – at one point the greedy
bugger had one in each arm – both alive and struggling. Most of the time, the
mantis would stalk the grasshopper and then lash out at the last second with
those arms of death but sometimes it would move above the grasshopper and then
leap on it. It is truly an awesome predator - and hours of entertainment both
parents and kids. Over the summer, its abdomen kept getting bigger and bigger
and then one day it laid an egg mass, so here’s hoping we have a cute clutch of
the little devils next spring. I can’t wait to release a bunch of baby
grasshoppers and watch the chaos.

A Quebec mantis (actually introduced from Europe).

The next thing that happened was that I started to find mantises
myself – first at Mt. St. Hilaire near Montreal where I was teaching a field
course (see the blog entry here)
and then also at the aforementioned barn. In each case, I would spend a long
time photographing them and following them around. I never saw them catch
anything in the wild but I did get a great appreciation for how their mobile
head makes you feel like you are interacting with them. If you get too close,
their head swivels around and looks right at you. No other insect can give you
the same feeling of communication. Eerie, it is.

The Hiroa-Dai karst tableland near Fukuoka.

Then this last week I went to Japan, where I participated in
a symposium on contemporary evolution at the annual meeting of the Japanese
Genetics Society. The symposium was organized by Yuya Fukano and my trip – and
that of fellow invitee Pierre-Olivier Cheptou – was funded by Tet Yahara with
organization help from Makiko Mimura. As most of the meeting was in Japanese,
we had plenty of time for excursions – and one of these was to Hirao-Dai, a
karst table land near Fukuoka. Along with three Japanese students and postdocs,
Pierre-Olivier and I had a great time walking around and looking at a whole
series of huge arthropods: wicked looking spiders, great carpenter bees,
massive hornets (which apparently kill more people in Japan than any other
animal), butterflies as big as birds, katydids spanning your palm, huge
grasshoppers, and yes brobdingnagian mantises. So when folks say that
everything is smaller in Japan, you can correct them by saying everything but
the insects. When these mantis turned their heads to look at me, I
involuntarily pulled back.

I see you.

Hanging out.

Come to my arms.

The mantises were everywhere – or maybe it was just that one
student (Ryosuke Iritani) was particularly good at spotting them. I decided
that if he were a superhero he would have to be called Mantis Boy – he even
looked a little bit like a mantis. (Come to think of it, mantis-like qualities
would seem better suited for a villain.) In addition to finding a number of
individuals of two species just hanging about apparently waiting for a hapless
hopper to wander by, we found one that was munching on prey it had just caught,
which brings me to a particularly macabre habit of mantises – they quite
happily eat their prey alive. As I was taking pictures of this mantis and its
prey, a huge carpenter bee, I noticed that the bee was still moving despite
having almost all of its’ abdomen eaten away. And the mantis was quite happily
tucking in while the bee continued to struggle – if a bit feebly. This isn’t a
rare thing, I think, as it regularly happens with our pet mantis at home. In
fact, I can still vividly remember it slowly engulfing the leg of a live and
struggling grasshopper like we would eat corn on a cob. Presumably they aren’t
being intentionally cruel – sometimes they first remove the head – but rather they
are just indifferent to the struggling and simply start to eat whatever part is
closest. But it is still pretty hideous stuff from the perspective of humans,
which always at least have the courtesy to kill their food first - right?

Yum. Nice and fresh.

Humans eat many curious things, especially in Asia. On the
second night after arriving in Japan, we went out to dinner and were looking at
the menu. Pictured (thankfully given the lack of English) were a whole series
of succulent looking meats tastefully arranged on plates. I asked what they
were and was surprised to be told in a matter-of-fact fashion that they were
whale. Really? Since Japan only engages in “scientific whaling,” I presume
this one provided some valuable scientific insight into cetaceans – perhaps it
was the N that made P less than 0.05. Seeing whale on the menu without fanfare brought
back memories of Norway, where my friends (Ole and Irene Berg) served me home-cooked
whale. I felt guilty enough at the time to
call Heather and ask her permission to eat it. I think she would have said no
if I hadn’t been standing in their kitchen with the food on the table. The
second time I ate whale was also in Norway, this time at a restaurant where I
didn’t find out what it was until after having a few bites. So I told these
stories to my Japanese hosts, particularly emphasizing the absurdity of calling
Heather to ask permission. Then in hopes that I wouldn’t have to call Heather, I
flipped the menu to see if something on the other side could divert attention
away from the whale. “And what are these I asked?” After a brief consultation,
the answer was “horse.” I had to laugh: if these were the only two things on
the menu, Heather would probably call me to insist that I eat the whale.

On the way back to my hotel after having dinner, I met Tet
Yahara and Jun Kitano, who took me for a second dinner and a fifth and sixth
sake. As we walked into the new restaurant/bar, I noticed a tank of squid.
Pretty cool I thought, much better than tropical fish, and then I realized what
they were there for. I commented to Tet, “So I suppose people get to pick their
own squid out for dinner.” Half an hour later and without warning (to me at
least) a squid arrived at the table. It looked VERY fresh. It was lying there
in a somewhat life-like pose and its mantle had been sliced into a series of
delicate an incredibly symmetrical sections that were still in the proper
position. Looking closer I noticed then squid was still moving its tentacles
and had waves of color moving across it. Was I about to channel a praying
mantis.

So it seems to me that this must be – at least for me – the
year of the mantis, and if I were to start all over again perhaps I might make
it the career of the mantis. But then I did also see mudskippers and tiger beetles,
which were almost as cool. Maybe I can start over multiple times.

Saturday, September 22, 2012

It may seem dead obvious to most of us that preserving
biodiversity is the most important legacy that we can leave to future
generations – but it turns out that most of us is not the same as most of
everybody. Instead, it seems that a large segment of everybody thinks that
biodiversity conservation somehow trades off with prosperity to the extent that
preserving biodiversity will decrease human well being. This recalcitrant
segment of humanity often strongly influences government policy, and so biodiversity
scientists have sought convincing arguments for why biodiversity is valuable
and important. One example is bioprospecting: many chemicals found in nature
have proven beneficial to humans and we can only assume that more such
chemicals are out there waiting to be discovered. We must therefore save biodiversity
in hopes of gaining those benefits before the species that could provide them
go extinct. Another big idea is ecosystem services.

Ecosystem services at the Gault Nature Reserve.

Arguments from ecosystem services embrace the notion that organisms
in natural environments make crucial contributions to ecosystem functions that
directly and immediately benefit humans, with particularly ubiquitous examples
being clean water, productivity, nutrient cycling, and pollination. An
immediately obvious limitation of a strict application of this argument is that
it might suggest we should simply identify those valuable organisms and
preserve them without worrying about the (expensive) rest. But maybe the rest
are providing key ecosystem services that we aren’t yet aware of, or maybe they
are somehow critical to the dynamics of the species providing known ecosystem
services. In recognition of these possibilities, biodiversity scientists have
spent considerable time establishing that biodiversity per se enhances
ecosystem function – with some of the most compelling evidence coming from experiments
that showed greater species diversity (of grasses for example) improves ecosystem
function (higher total productivity for example).

The relationship between biodiversity and ecosystem function
is not universal, linear, or (often) particularly strong. For me, the most in-your-face
demonstration of ambiguity is that clean water (for example) can be found from
the tropics to the Arctic despite the fact that species diversity differs by
orders of magnitude. (And I can’t help but think of those images of Afganistan
with lots of people walking about but not a plant or source of water in sight.)
Moreover, many of the ecosystems from which we now obtain our clean water are
incredibly impoverished compared to what they looked like centuries or
millennia previously. So ecosystem services can be maintained – or perhaps even
enhanced (clean water is perhaps hardest to come by in the tropics) – through
decreased species diversity.

I suspect that weak and inconsistent relationships between
biodiversity and ecosystem function are symptomatic of the reality that
biodiversity also provides ecosystem
disservices. Some species are just flat-out
bad for clean water, productivity, nutrient cycling, and pollination. And, of
course, many species are unequivocally bad for humans in general, most
obviously a number of diseases. So perhaps we have, on the one hand, a positive
relationship between biodiversity and good aspects of ecosystem function
(services) but also, on the other hand, a negative relationship between
biodiversity and bad aspects of ecosystem function (disservices). The product
of these two lines yields the optimal level of biodiversity, right? Let’s
manage for that – problem solved!

Please note tongue firmly in cheek.

It would be complete nonsense to actually manage in this
fashion but the absurd point highlights some difficulties of using ecosystem
services as the primary argument for biodiversity conservation. In particular, focusing
on ecosystem services seems to more obviously argue for the preservation of particular
species and the elimination of other particular species (at least when we know
which those bad species are). This
brings to mind a currently controversial topic in ecology and conservation
biology: “assisted migration” or “assisted colonization.” This is the idea that
– particularly under climate change – the optimal conditions for some species
will be shifting from their current location to some new (perhaps more northward)
location, and that species might have trouble moving to those new locations
owing to limited dispersal ability or man-made or natural barriers. For these
species, the argument goes, we should get off our butts and actively move
individuals to the more appropriate location. The counterargument is that this
tantamount to intentionally introducing species to locations where they did not
previously exist and the long history of negative impacts of invasive species
suggests that this is bad for biodiversity and productivity and services.

Assisted colonization buys into a hands-on approach to
management. Another hands-on approach might be called “assisted elimination” (or assisted extinction or assisted
extirpation). Acknowledging ecosystem disservices provided by particular
species, perhaps we should actively seek out and exterminate those species. We
did this for small pox and we try to do it for invasive species or pests all
the time. This seems like a pretty sure-fire management strategy given that we
can all surely agree on particular species that are just straight-up bad and without
which the world would be a better place: HIV, TB, lyme disease, malaria, dengue,
mosquitoes, rats, poison ivy (at least near my house), small yappy dogs
(particularly my neighbor’s) … Hmmm, mosquitos do many things in the
environment and are critical to the existence of a number of other species,
such as some bats, dragonflies, and birds. So are mosquitoes or poison ivy or
rats really a disservice? What is their optimal diversity or abundance? How
would their service-disservice lines intersect? We are on the edge of a
slippery slope here.

The point of this post isn’t to argue that we should promote
management strategies based on the acknowledgement of ecosystem disservices or that
we should or shouldn’t promote assisted elimination. It is instead intended to
illuminate the difficulty of making arguments for biodiversity preservation solely
from a consideration of ecosystem services – and also to help remember the
limitations of a hands-on approach to management. We just know too little. What
we really should be doing is preserving biodiversity per se – specifically because
of our ignorance. And the best way to preserve biodiversity is to preserve
habitats and (yes, Andy) their connectivity.

A biodiversity of scientists enhanced services and disservices at the Gault Nature Reserve.

(The ideas in this post were motivated by discussions at the
just-finished DIVERSITAS EcoEvol workshop held at McGill’s Gault Nature Reserve
in Quebec, Canada. Participants included myself, Andrew Gonzalez, Paul Leadley,
Cornelia Krug, Makiko Mimura, Talisker, Bob Holt, Mark Kirkpatrick, Jon Bridle,
Luc De Meester, Dominique Gravel, Jonathan Davies, Virginie Millien, Ulrich
Mueller, Highland Park, Justin Travis, Jessica Hellmann, William Godsoe, Mark Urban, Brian McGill, and
Rob Coulautti. I am quite certain that many of the other workshop participants
will disagree with the ideas expressed in this post and so I hope they will
provide comments that devastate what I have here suggested.)

All of these research “fields” with their wonderfully jargony
titles involve the study of interactions between ecology and evolution. Surely
they can all be united into a single framework under a unified conceptual model
of eco-evolutionary dynamics: the “Kumbaya Model” if you will. Adopting a motivating
degree of naiveté, the working group meeting from which I just returned had set
the Kumbaya Model as one of its key goals.

The previous two meetings of this working group, both funded
by the Quebec Centre for Biodiversity Science, had taken place at the Gault
Nature Reserve, McGill’s field station/mountain near Montreal. The working
group then splintered (or adaptively diversified) into three subgroups: one
considering evolutionary rescue, one considering rates and patterns of trait
evolution, and one working on the Kumbaya Model. An original driving force
behind the overall umbrella working group was Eric Palkovacs, previously at Duke
University. In the last year, Eric moved to UC Santa Cruz and so when a meeting
location for the third subgroup was debated, California was a promising
candidate. Tipping the balance, my family has a vineyard and winery in Napa (http://www.hendrywines.com/) that could
host us for free.

The Chardonnay and Pinot Noir harvest was in full swing.

Last Friday, ten eco-evo types (yes, Jonathan Davies, you too
now fall under this appellation) descended on the Hendry Vineyard in Napa – and
particularly on the house of my brother Mike, his long-to-be-suffering wife
Molly, and their enthusiastic dog Jake. For three days, we held hands, sang
Kumbaya, and asked of the eco-evolutionary fields “why can’t we all just get
along”? When inspiration flagged, we sought more of it through walks, tours of
the vineyard and winery, a lot of very fine wine, and a barbeque banquet to end
all banquets (Mike and Molly crafted a feast for us that included Mike-caught
coho salmon from our cabin in BC and Molly-grown Asian pears from the garden
below their house.)

Jonathan used locally available fossils to time-calibrate a large fish phylogeny.

On one of the walks, we were privileged to witness and
thereby recognize and appreciate the Jake Reset Effect. At this time of year, reservoirs
on the vineyard have very little water in them and are just a few feet deep.
With thoughts of maybe initiating some eco-evolutionary research in these
reservoirs, we had walked over to have a look – and Jake had come along as a
guide. As soon as we arrived, Jake followed his muse and waded into the water
and around the reservoir. In doing so, he stirred up mud from the bottom in big
plumes. David Post had been standing beside the reservoir and waxing poetic on
the power of Daphnia as a model system for studying eco-evolutionary dynamics
when he noticed Jake wading through the sediments. “Noooooo …” he wailed “Jake
you are stirring up the Daphnia egg bank and destroying decades of adaptive evolution.”
Although he was being a bit histrionic, his assertion could literally be true:
small and rare disturbances, such as a dog walking through a reservoir, could reset
or at least remix the past evolutionary history of Daphnia and shuffle its genetic
variation across the decades of evolution buried in the sediments. So, in one
fell swoop, it was too late and so much for Daphnia research in the Hendry
Vineyard Reservoir. At least the reservoir still has stickleback and I doubt
Jake can so easily reset their evolution.

"... and another cool thing about Daphnia is ..."

Although walking and drinking wine might seem like frivolous
distractions, we actually did make great progress on the Kumbaya Model. I don’t
want to spill the beans here, because you will soon (or late) be able to read
it in Science or, failing that, the Proceedings of the Southwest Santa Cruz
Natural History Society. We, and Eric in particular (see his previous blog entry),
have railed about the fact that eco-evo review papers are more common than eco-evo
studies that actually present real data, and so we promise that this new Kumbaya
Model paper will be the review to end all reviews – the one review to rule them
all. In the meantime, we will seek new and clever ways to invade the vineyard again
and perhaps collect some real data as a part of Fanie Pelletier’s Global
Eco-Evolutionary Research Consortium.

A nexus of the consortium? (Photo by Mike Hendry.)

So what could we do? An excellent way to study the role of
evolution in ecological dynamics is to have two replicate populations (such as
Daphnia in two ponds) where one population is allowed to evolve adaptively while
the other is not. And one of the best ways to prevent directional adaptive
evolution is to increase mixing between gene pools that have been selected in
different environments, such as populations from different places or that exist
at different times – think Daphnia eggs from different depths in the sediment
(and therefore different years). As there are two reservoirs on the vineyard, I
am thinking we can just have Jake regularly wade through one (adaptation interrupted)
but not the other (adaptation perfected). I can see the paper title now: “Experimental
Manipulation of the Jake Reset Effect Validates the Kumbaya Model of
Eco-Evolutionary Dynamics.” The only question is where Jake should be in the author
list.

Thursday, September 6, 2012

This is going to be a long post, so put it off for a lazy post-lunch lull, get yourself a cup of coffee, and prop your feet up on your favorite ottoman. You have been warned.

I recently participated in the Helsinki Summer School on Mathematical Ecology and Evolution, which this year focused on the theory of speciation. The school was a part of the larger series of schools, workshops and conferences organized by FROSpects, an ESF Research Networking Programme that has been doing a great job of supporting and promoting speciation research – I've attended several of their events in the past, such as the Abisko Winter School in 2011 and the Speciation 2010 conference in Austria, and they have had a big influence on my path as a graduate student. I'll talk about the Helsinki summer school in a moment, but first, I can't resist giving you a brief touristic interlude.

Since I've never been that far northeast in Europe before, I seized the opportunity and went for an overnight visit to St. Petersburg (only three and a half hours away by train!), which was fun but exhausting. The high point for me was seeing the iconic Church on the Spilled Blood, which was every bit as spectacular in person as it is in photos:

The Hermitage was amazing too, and could have taken up much, much more than the half-day I could give it. It was heartbreaking to have to hurry through rooms filled with works by Cézanne, Matisse, Van Gogh, Corot, Caravaggio, Gauguin, Pisarro, Degas, Renoir, Seurat, Vlaminck, Picasso... I will have to go back some day. They had great exhibits of ancient art and artifacts from around the world, too, which I enjoyed a lot, and tons of Middle Ages and Renaissance art that I mostly skipped due to lack of time. (I did suffer the tourist hordes to glimpse the two very famous da Vincisthere, though.)

One lovely thing about the Hermitage is that unlike many stuffy, arbitrarily restrictive museums, they mostly allow you to photograph their exhibits (but no flash, of course, since it can damage the art). The first photo below shows an example of the opulent interior of the museum, which was once a palace; the second shows a nifty Kandinsky that caught my eye; and the third shows a remarkable mask and breast collar for a horse, from around the 3rd-4th century B.C., from the Pazyryk culture of the Altai – a region in central Siberia that I had never even heard of before:

I got to spend a little time in Helsinki, too, on the way in and out, which was great. It has a beautiful downtown area with an open-air market, small side streets and lovely churches:

And also quite a remarkable island fortress called Suomenlinna that you can explore, walking both on top of and inside of the walls and admiring the old cannons:

Amusingly, the name Suomenlinna is Finnish for "Finnish castle", while the Swedish name for the fortress, Sveaborg, is Swedish for "Swedish castle". (It was built by the Swedes in 1748, then was captured by the Russians in 1808 – but I don't know whether their name for it would translate to "Russian castle" – and then became Finnish when Finland became independent in 1917.)

The school was actually held, not in Helsinki, but in Turku, another town in Finland to the west of Helsinki. I didn't have much time to see Turku – in part because I managed to crack a rib early in the summer school, attempting to play soccer one fine evening, which subsequently limited my mobility – but the Turku cathedral dates back to the 13th century (although much of it was rebuilt after fires much more recently) and was quite groovy.

Well, I'm supposed to be talking about the summer school, aren't I! If I were Andrew, I would find a way to weave some quirk of my travel experiences together with musings about evolution to form a unified tapestry. Suomenlinna and the evolution of defenses against predation and parasitism? The Hermitage and the adaptive value (if any) of the human sense of aesthetics? But I am not feeling inspired, so please pardon the abrupt transition from tourism to biology.

The school had five main speakers: Sergei Gavrilets, Nick Barton, Sander van Doorn, Eva Kisdi, and Dan Bolnick. First, however, Mats Gyllenberg opened the school with a talk about competitive exclusion, limiting similarity, and coexistence; this is a central question for speciation theory, of course, whether coexistence occurs with secondary contact after divergence in allopatry, or is an ongoing issue as divergence proceeds in sympatry or parapatry. Ultimately, all life on our planet descends from one common ancestor, and yet that life has managed to subdivide the niche of "planet Earth" (which one could imagine being dominated by one extreme generalist species) into enough partitions to support the many millions of species now extant, finessing the Principle of Competitive Exclusion in a myriad ways. The upshot of Gyllenberg's talk, which I believe was based upon work by Dieckmann, Metz, and Meszéna, was that coexistence of an infinite number of species is mathematically possible – the variety of biodiversity could be continuous, in other words, rather than divided into discrete packets that we call "species" – but that this result is not robust, and collapses into a finite number of discrete species subdividing the available dimensions of niche space given any sort of perturbation from stochasticity. Paraphrasing him, the messy realities of biology prevent the coexistence of infinitely many types.

Sergei Gavrilets gave quite a fast-paced set of lectures (despite his laptop dying at the beginning of the school). He started with the history of population genetics and the earliest forays into mathematical modeling and theoretical speciation research. Then he discussed fitness landscapes of various kinds, evolution on them, peak shift models and the difficulty of getting across valleys, the Bateson-Dobzhansky-Muller model of neutral mutations leading to reproductive isolation due to epistatic interactions, and movement along "nearly neutral networks" on high-dimensional "holey adaptive landscapes." Much of this covered similar ground to his very important 2003 paper "Models of Speciation: What have we learned in 40 years?" Then he wrapped up with an overview of models of non-random mating and sympatric speciation, touching on the importance of a cost of choosiness in inhibiting the development of assortative mating. Little is known empirically about costs of choosiness, but this is a central consideration for speciation theory. Empiricists, take note!

Nick Barton walked us all through the rather intricate details of a remarkably powerful extension to population genetics that he has developed with Michael Turelli and Mark Kirkpatrick. This method allows the effects of dominance, epistasis, and linkage disequilibrium to be accounted for much more tractably than with more traditional methods. In many situations these effects can be ignored, because populations are often well-mixed (because selection is weak compared to recombination), and so selection acts chiefly on the marginal, additive effects of genes. Not so in speciation theory, however, because speciation typically implies strong selection, non-random mating, and mixing of populations between divergent habitats, all of which cause linkage disequilibrium, and because reproductive isolation is often based upon epistasis, and so forth. Indeed, he said that speciation might best be formally defined in terms of linkage disequilibrium; so clearly speciation theory must tackle the causes and consequences of that! In later talks Dr. Barton used his method to explore speciation in the Levene model, with reference to Felsenstein's classic 1981 "Santa Rosalia" paper, and then wrapped up with a survey of models of parapatric speciation and clines.

Sander van Doorn talked about the role of sexual selection in speciation. Dr. van Doorn is one of those speakers who is so eloquent that he makes very complex ideas seem simple... until, a few moments after he stops speaking, the illusion of perfect understanding that he had cast over you melts away. Sexual selection is a multifarious topic. There are cue traits and preference traits, ornaments and honest signals and nuptial gifts and parental investment, male-male competition and female choice, good-genes models and magic-trait models and Fisherian runaway sexual selection models. There is the problem of coexistence of ecologically identical species after speciation due to sexual selection, and the problem of the origin of variation in mating preferences. He surveyed a wide range of models touching upon these and other issues, and I'm not going to try to summarize it all except to say that it was very interesting and I look forward to a review paper from him covering the same ground!

Eva Kisdi gave a very clear and gentle introduction to adaptive dynamics, starting with the Levene model and the fine-tuning problem, then introducing the tools of adaptive dynamics from pairwise invasibility plots to the criteria for classifying singular points. One pithy statement that she made stuck with me: natural selection is usually called "the survival of the fittest", but when an evolutionary branching point is present, it instead selects for increasing diversity! Perhaps that nicely encapsulates why I find speciation theory fascinating. She walked us through a very cool proof of a method of determining the constraints on trade-off functions that will produce evolutionary branching in any given model – even models for which analytical results cannot be obtained. In later lectures, she showed how to do adaptive dynamics for sexual populations, and then applied that method to a magic trait model.

Finally, Dan Bolnick grounded the school with talks (and a workgroup that I participated in) on the interactions between theory and data. He started with a summary of what he thinks are the big questions in speciation research today, and summarized contributions from theorists and empiricists to those questions. I found this to be a very helpful clarification of the "big picture": why we were all gathered together in a classroom for a week to talk about speciation. He then took a step back and talked about how exactly theory and data can interact, what theory typically does for empirical work, what empirical work typically uses theory for, and the limitations inherent in those interactions. He proposed that there are four types of interaction. The first is that theory and empirical work can be "in the same room", sharing a biological context but not actually meeting or speaking to each other. Alternatively, work can be data-driven, with novel empirical findings driving new theory to explain what was observed, or theory-driven, with interesting theoretical findings pushing empirical investigation of questions that had not previously been examined. Most intimately, there can be a reciprocal interaction in which each prompts new work in the other, in a feedback loop between theoretical refinements and new experiments. He capped things off with a tale of Tribolium, an insect that has been leading him and a postdoc in his lab on a wild goose chase through both theory and experiment, with a mysterious cliff-hanger ending that has yet to be resolved.

Other speakers touched upon the interaction between theory and data too:

Dr. Gavrilets, for example, opined that the maturity of any scientific field can be assessed by its level of mathematical sophistication, and that evolutionary biology is therefore the most mature subfield of biology – a provocative claim! – and also quoted Haldane as saying that one should mistrust any verbal argument when an algebraic argument would instead be possible, and that skepticism is warranted whenever not enough facts are known to permit an algebraic argument from being formulated.

Dr. Barton emphasized that he thinks there is a need to relate theory more to things that we can actually measure, and for empiricists to then actually measure those things. For example, adaptive dynamics predicts that populations will evolve towards stationary points and then often experience disruptive selection; this is an extremely important prediction, but it has not been tested. Can it be tested? If not, can the predictions of adaptive dynamics be framed somehow in a more testable way?

Dr. van Doorn pointed out that in reality, a species can respond in many different ways to selection pressures: evolution of dominance, concentration of genetic variance at just a few loci (evolution of polymorphism), broadening their resource utilization curve, evolving sexual dimorphism, evolving plasticity... but because of the kind of models we build, with very little genetic flexibility or realism, we have little to say about when these different outcomes should be expected instead of speciation. Can we make better models? How can empirical data help us to do so?

Dr. Kisdi, in her discussion of trade-offs, emphasized that so little is known empirically about the shape – or even the existence! – of trade-off functions in nature that theorists have more or less free rein to speculate in this area. In the workgroup that I participated in with Dr. Bolnick, we returned to this issue in more depth, and one of my fellow students, Pavel Payne, gave a brief presentation about what little is known about trade-offs in nature. How can we know so little about something so central? What can we can do improve this state of affairs? And are there ways that theorists could help what what must ultimately be an empirical project in this area?

For me, these discussions of the interaction between theory and data were the most thought-provoking part of the summer school, because they spoke to my developing identity as an evolutionary modeler. What does it mean to be a modeler? If your models are untestable, are you still doing biology, or are you doing pure mathematics? Is evolutionary modeling an undertaking whose primary aim is to inform and explain empirical work, or is it a field that stands on its own, and that does not necessarily need to be useful to empiricists to be worthwhile? Alternatively, if Dr. Gavrilets is right that it is the mathematical models that show the maturity of the field, then is empirical work in biology perhaps an undertaking whose primary aim should be to supply data, parameter values, and scenarios as fodder for modelers? Do theory and data have a mutualistic relationship, or a commensal relationship, or a competitive relationship – or is one perhaps even a parasite of the other? Is the "reciprocal interaction" between theory and data that Dr. Bolnick described the best way for the two to interact, or are other ways – even just being "in the same room" – just as good, or perhaps even better? There were as many answers to these sorts of questions as there were participants at the school, and that made for very rich and interesting discussions, to me.

I got to go with my friend in Helsinki to a traditional public wood-burning sauna (awesome!), and then several times I used the sauna at the convention center where the summer school was held, too. So I can definitively state that saunas are not only good in theory; I have confirmed this experimentally, and I have replicated my results several times in independent trials. This, I think, is the best of all possible outcomes of the interaction between theory and data. May all your research endeavors go so well.

And perhaps that's where I can find a thread to tie together my touristy travelogue with the summer school. Ultimately, for me, it is the real world that I wish to understand and explain. Reality is more beautiful than any mathematical model, to me, and mathematics is just one tool (albeit both a beautiful and useful one) to help us understand reality. No model would ever predict the Church on Spilled Blood. Ergo, tourist snaps of St. Petersburg. And on that note, let's shift back to the tourism to wrap things up!

At the end of the school, we spent the final evening in Naantali, a charming little tourist trap on the coast. For some reason, Naantali is associated with the Moomintrolls, a set of children's book characters, and there was Moomin-kitsch everywhere. I grew up reading the Moomin-books, though, so it was fun for me (and I now regret not buying something related to the Hattifatteners, my favorite part of those books). We had a really yummy dinner at a local restaurant and enjoyed the views of the Baltic and the amazing Archipelago Sea off the coast of Finland. Here's a Moomin-flag for the Moomin World at Naantali, and then a shot of Dan Bolnick looking for (and finding!) stickleback in the waters of the Baltic, with the beginnings of the archipelago behind him:

The summer school was organized by Eva Kisdi and Tadeas Priklopil, who did a great job of making the event run smoothly. Thanks to Eva and Tadeas, to the lecturers who gave so much of their valuable time, to my fellow students for making it fun, and to FROSpects and the other organizations that made this school possible!

Participants at the summer school. (I'm the guy in the lowerright who is so white that he looks like he'd glow in the dark.)

Those who want more travel details and photos will eventually be able to find them on my photography website, cloudphotographic.com, but they won't be there for a couple of months, probably, and by then you will all have forgotten.

Wednesday, September 5, 2012

It may feel like a week, but another month has gone by, and it is time for Carnival of Evolution #51! The theme this time is "Darwin's Restaurant", and this blog's contribution, Ronald Bassar's post on evo -> eco in guppies, is designated as an entrée. Bon appétit!